1. Technical Field
This application relates to a stent, and more particularly to a stent that is compressible to small diameters to enable access to small vessels or ducts within the body.
2. Background of Related Art
Stents are well known in the medical arts for the treatment of vascular disease (e.g., vascular stenosis, aneurysms, etc.). Stents are prostheses which are generally tubular in form and which typically expand radially in a vessel or lumen to maintain its patency or for other therapeutic purposes. For deployment within the body's vascular system, some stents are mounted onto a balloon angioplasty catheter for deployment by balloon expansion at the site of a stenosis, an aneurysm, or other duct in need of treatment. Balloon-expandable stents are typically crimped onto the outer surface of a balloon located near the distal end of a catheter. The stent is expanded by inflation of the balloon and maintains its expanded configuration by virtue of being plastically deformed during the expansion process. Self-expanding stents, on the contrary, need little or no external force to move them from a compressed configuration to an expanded configuration. Self-expanding stents either self-expand due to exposure of environmental factors (e.g., body heat) and/or are radially constrained in a compressed/reduced diameter position on or within a delivery device and self-expand toward an original diameter when released from the delivery device so as to exert a radial force on the wall of the body lumen. Self-expanding stents are generally composed of shape memory alloys such as Nitinol, a nickel-titanium shape memory alloy, which can be formed and annealed, deformed at a low temperature, and recalled to its original shape with heating, such as when deployed at body temperature in the body.
Conventional percutaneous delivery of a stent to a treatment site generally includes introducing a guiding catheter having a preformed distal tip into the vascular system of a patient by way of, e.g., a conventional Seldinger technique, and advancing the guiding catheter within the vasculature until its distal tip is seated in the ostium of a desired artery. A guidewire is then advanced through an inner lumen of the guiding catheter until the distal end of the guidewire is placed across the treatment site. A stent delivery device carrying the stent is then advanced over the guidewire to properly position the stent across the treatment site. Once positioned, the stent is expanded for permanent placement at the treatment site.
Conventional stent delivery catheters share a common feature in that they are required to have a guidewire lumen to facilitate advancement of the catheter over the guidewire for placement of the stent. As a consequence, the guidewire lumen necessarily adds to the cross-sectional profile of the device and prohibits the use of these devices in the treatment of certain small diameter vessels and/or vessels located within tortuous regions of the vasculature (e.g., vessels located within the coronary and intracranial vasculature).
In commonly assigned U.S. Pat. No. 6,989,024, the entire contents of which are incorporated herein by reference, for all they teach or suggest, are disclosed methods and systems for delivering a vascular prosthesis (e.g., stent) that is mounted on a distal segment of an elongate wire or hyptoube. A major advantage of the wire-based delivery devices described in U.S. Pat. No. 6,989,024 is that the delivery devices obviate the need of a guidewire lumen in the delivery devices, and hence, facilitate the delivery of stents and other vascular prosthesis to small diameter vessels located within the tortuous anatomy of the body. For example, in one embodiment the vascular prosthesis is mounted on a reduced diameter portion of a wire, resulting in an overall reduced profile. Proximal and distal radiopaque marker bands, functioning as proximal and distal stops for the stent, are also described for certain embodiments. Reduced profile delivery systems are also disclosed in commonly assigned co-pending application Ser. Nos. 11/703,341 and 11/703,342, both filed on Feb. 7, 2007. The entire contents of these applications are incorporated herein by reference, for all they teach or suggest.
The present application provides a stent compressible to small diameters to provide access to small diameter vessels for use in neurovascular, cardiovascular as well as other clinical applications, and can be delivered via the wire-based devices disclosed in U.S. Pat. No. 6,989,024, in the Ser. Nos. 11/703,341 and 11/703,342 applications, or other devices, such as catheters.